This invention relates to a distance information obtaining device for use in obtaining distance information related to a distance between the device and an object having a bulk.
A distance information obtaining device of the type described, is disclosed in an article which is published by Johji Tajima, the instant applicant, under the title of "Rainbow Range Finder Principle for Range Data Acquisition" in "International Workshop on Industrial Application of Machine Vision and Machine Intelligence" held by IEEE in 1987, pages 381 to 386. The range finder is used as the distance information obtaining device.
Another distance information obtaining device of the type described, is disclosed in U.S. Pat. No. 4,864,395 issued to the instant applicant and assigned to the instant assignee.
In order to deal with the object by using, for example, a robot arm or magic hand, it is necessary to sense three dimensional distance information from an observation position or a predetermined position to each point on the object. A distance information obtaining device is for obtaining the distance information by using a picture signal of the object. The distance information obtaining device is also used in obtaining the distance information when the object is a human body.
The distance information obtaining device comprises an optical beam generator, such as a lamp, for generating an optical beam having a plurality of wavelength components. In other words, the optical beam is a white light or the daylight. Supplied with the optical beam, a diffraction grating illuminates the object by a monochromatic beam having a selected one of the wavelength components. Thus, the diffraction grating serves as an illuminating unit for illuminating the object by the monochromatic beam.
An image pickup device, such as a color television camera, is located at the observation or predetermined position. The image pickup device picks up an optical image of the object and produces a picture signal. Connected to the image pickup device, a processing unit processes the picture signal into a processed signal representative of the distance information in the manner which will later be described.
On obtaining the distance information by a conventional distance information obtaining device, it is necessary to prepare a special environment in which environment light of the object is cut off. In order to avoid preparing the special environment, the optical beam generator may be made to generate the optical beam having an intensity which is higher than that of the environment light of the object. When the object is a human body, illuminating the human body by the optical beam of high intensity for a long time has a harmful influence on the human body.